1. Technical Field
The present invention relates to a conductive ink composition and a method of forming a conductive pattern using the conductive ink composition.
2. Discussion of the Related Art
An optical patterning method using a photolithography process is used for forming a conductive pattern. However, the optical patterning method using the photolithography process requires many processing steps and is complicated, so that the manufacturing costs for forming the conductive pattern are increased. Types of substrates usable in the optical patterning method may be limited due to an exposure process and a development process. Furthermore, environmental pollution may be caused by gas and wastewater generated in the exposure process and the development process.
A direct drawing method using inkjet printing has been developed in place of the photolithography process.
The inkjet printing method directly draws a desired pattern on a substrate. The inkjet printing method can be used for large-size printing and various types of substrates. Thus, manufacturing time and manufacturing costs may be reduced. Furthermore, the inkjet printing method does not include an exposure process and an etching process that does not generate environmental pollutants.
The inkjet printing method for forming a conductive pattern uses a conductive ink that is a liquid material having a low viscosity to form the conductive pattern. The conductive ink may include, for example, molten metal, a conductive polymer, a metal salt, or metal nanoparticles. The molten metal has a relatively high conductivity. However, the molten metal has a high temperature, and thus the molten metal is difficult to apply to actual inkjet printing processes. Poly(ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT/PSS), which is a conductive polymer, has a relatively high conductivity among conductive polymers and relatively high stability in air. However, the conductivity of the PEDOT/PSS is about 0.1 S/cm, that is much less than the conductivity of a metal at about 105 S/cm to about 106 S/cm. Thus, research has been conducted on an ink containing metal nanoparticles capable of having a relatively high conductivity through a heating process at a relatively low temperature.
The metal nanoparticles may include, for example, gold, silver, platinum, or copper. The ink containing copper nanoparticles has low manufacturing costs and a relatively high conductivity. However, the ink containing the copper nanoparticles has relatively low oxidation stability.